wcf advanced activity development

8/12/2019 Wcf Advanced Activity Development

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Session Code: CV.27

Integrating WCF andWorkflow, Advanced activity

development

Marcel de VriesMicrosoft MVP Team System

http://blogs.infosupport.co m/marcelvmarce

[email protected]
mailto:[email protected]://blogs.infosupport.com/marcelvmailto:[email protected]:[email protected]:[email protected]://blogs.infosupport.com/marcelv


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Agenda

Integrating WCF in workflow Building activities basics Design time behavior

Type Converters Activity Designer Runtime behavior

Activity Code Generator Additional features

Attached Dependency properties Activity Validator

Summary


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Integrating WCF in workflow

WCF requires a class that implements a servicecontract and that is hosted in a service host

[ServiceContract(Namespace= "http://www.beyonddotnet.com/WCFTestInterface" )]public interface WCFTEstInterface{

[OperationContract ]string SayHello();[OperationContract(IsOneWay= true, Action= "DoNothing2") ]void DoNothing();

}

public class WCFTEstInterfaceImpl : WCFTEstInterface{

public string SayHello(){}public void DoNothing(){}

}


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Workflows are classes derived from activityand are hosted in a WorkflowRuntime

How can we combine the two? Create activities that can hold the service

operation definitions Generate a class that implements the interfaces

and applies the correct attributes

Create an implementation that can bootstrap theload/creation of a workflow when a WCF callcomes in

Integrating WCF in workflow


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Workflow Host e.g IIS

Integrating WCF in workflowGenerated codehandlingthe incoming call

Load/Create WF

Process WF

Return result

Client


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Activity Component ModelEach activity has an associated set of componentsComponents are associated through attributes on the Activity DefinitionIf not specified, parents attributes are applied

Required

Optional(defaults provided)

[Designer(typeof(MyDesigner))]

[ActivityCodeGenerator(typeof(MyCodeGen))]

[ActivityValidator(typeof(MyValidator))]

public class MyActivity: Activity {...}

Activity

CodeGenerator

Designer

Validator

Serializer Services

Workflow Runtime


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Building the activities Design time behavior

Pick interface using WF type picker dialog Create a dropdown containing methods available on Interface Add parameter that can be bound based on selected method in

interface

Generate WCF code that handles incoming call Validate if activities are configured correctly

Runtime behavior Register an event queue to wait on until notified by generated

code to start processing

At continuation bind parameters based on binding expressions Output activity returns results


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Implementing Design timebehavior


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Design time behavior Interface Property

Implementing the Interface property Dependency property of type Type Attached a TypeBrowserEditor using attributes

Need to implement ITypeFilter to show only interfaces we are

interested in

public bool CanFilterType( Type type , bool throwOnError){

// Display only interfacesreturn (type.IsInterface);

}[Browsable( false )]public string FilterDescription{

get { return "Choose an interface you want to expose as a ServiceContract" ; }}


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Design time behavior Method Property

Method property needs a custom value provider,since it must show all methods available in theselected interface Done by adding attribute to property providing custom

TypeProvider When a method is selected in the grid you need

to trigger that the parameters are exposed to theproperty grid as bindable properties Triggering is done by specifying attribute to the

Method attribute [RefreshProperties(RefreshProperties.All)]

And is handled in the designer OnActivityChanged


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Design time behavior Parameters property

Parameters property needs to be a dynamiclist of bindable parameters depending on theavailable arguments of the selected Methodin the interface This is done by creating the Parameters property

of type WorkflowParameterBindingCollectionand implementing designer behavior

Designer takes care of adding bindable propertiesto this collection in the PreFilterPropertiesmethod


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Design time behavior

Implementing the designer PreFilterProperties must use reflection to get

all parameters for the selected method Adds a new PropertyDescriptor for each

parameter Eacht property is Bindable in the property grid

Each property has the BindUITypeEditorattached


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DEMO:Creating the design timebehavior

Implementing Design time behavior forWCFActivities Type Property Method Property Parameters property


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Implementing Runtime behavior Runtime behavior must do the following

For each incoming message load or create theappropriate workflow

Yield the thread to the workflow so it can execute until

it becomes idle in the WCF Input activity Register a synchronization object when output isgenerated by the workflow

There is an associated output activity Yield the thread again to execute the workflow

between the input and output activity Binds the message data to parameters set in the designer Communicate back the results of the call when

synchronization object is signaled


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Workflow Host e.g IIS

Generated codehandlingthe incoming call

Load/Create WF

Queue MessageData

Return result

Yield Thread

Register andwait on queue

Register WaitObject

Yield Thread

Dequeue &Bind params

Wait for WaitObject


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Implementing Runtime behavior WCFInput Must register a queue to receive the data

Done using a base class that handles queue management. Only Implement ProcessQueueItem

Generated code will pass message data for

processing in the queue

protected override bool ProcessQueueItem( ActivityExecutionContext context,object item)

{

object [] inputParameters = (object [])item;ProcessParameters(inputParameters);return true ;

}


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Implementing Runtime behavior

ProcessParameters binds the providedmessage data to the workflow properties

private void ProcessParameters( object [] inputParameters)

{MethodInfo methodInfo = InterfaceType.GetMethod(MethodName);int parameterIndex = 0;foreach (ParameterInfo paramInfo in methodInfo.GetParameters()){

if (Parameters.Contains(paramInfo.Name)){

WorkflowParameterBinding parameterBinding = Parameters[paramInfo.Name];parameterBinding.Value = inputParameters[parameterIndex++];

}}

}

Activity metadata

WCF message data


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Demo

Show generic WCF call handling Show Input activity implementation


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Implementing Runtime behavior

Most of the WCF handling can beprogrammed in a base class that handleseach call Only parameter binding is done in the input

activity itself, rest is WCF plumbing Some code needs to be generated to expose

the service contract This is done using an ActivityCodeGenerator

Generate a class that implements the selected methodsignatures in the input activities Add WCF attributes to those methods so they can be

exposed to WCF


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Implementing runtime behavior

Activity Code Generator Invoked during the compilation cycle of a

workflow project

Use CodeDom to add you custom code Use reflector to see what you generated WF Program compilation steps:

1. XAML deserialization & code generation

2. Activity Validation3. Activity code Generation4. Code Compilation


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Implementing runtime behavior

What needs to be generated? The call to HandleWCFCall for each input

activity in the workflow[ServiceContract (Name ="TestWorkflow1" )]public class TestWorkflow1_wcfContractImpl : WCFCallHander { // Methods

[OperationContract ( Action ="ActivatingCall" )]private string ActivatingCall ()

{object [] p r m t rs = new object [0];return (string ) base .HandleWCFCall (true , false , typeof (TestWorkflow1 ),

"WCFTEstInterface" , "ActivatingCall" , "System.String" , parameters);}

}
http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.ServiceContractAttribute/.ctor()http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.ServiceContractAttribute/property:Name:Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1_wcfContractImplhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://WCFActivities:1.0.0.0:e316e0e29ca8f225/WCFActivities.WCFCallHanderhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.OperationContractAttribute/.ctor()http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.OperationContractAttribute/property:Action:Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1_wcfContractImpl/ActivatingCall():Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://WCFActivities:1.0.0.0:e316e0e29ca8f225/WCFActivities.WCFCallHander/HandleWCFCall(Boolean,Boolean,System.Type,String,String,String,Object[]):Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://WCFActivities:1.0.0.0:e316e0e29ca8f225/WCFActivities.WCFCallHander/HandleWCFCall(Boolean,Boolean,System.Type,String,String,String,Object[]):Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Objecthttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1_wcfContractImpl/ActivatingCall():Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://mscorlib:2.0.0.0:b77a5c561934e089/System.Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.OperationContractAttribute/property:Action:Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.OperationContractAttribute/.ctor()http://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://WCFActivities:1.0.0.0:e316e0e29ca8f225/WCFActivities.WCFCallHanderhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://TestLibrary:1.0.0.0/TestLibrary.TestWorkflow1_wcfContractImplhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.ServiceContractAttribute/property:Name:Stringhttp://www.aisto.com/roeder/dotnet/Default.aspx?Target=code://System.ServiceModel:3.0.0.0:b77a5c561934e089/System.ServiceModel.ServiceContractAttribute/.ctor()


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Activity code generation

Done by building an ActivityCodeGenerator

You receive a codedom representation ofyour workflow implementation Search for a definition of a class called

_wcfimpl If not found create one using code dom and adding

it to the namenspace Add a new method signature using code dom

to the generated class


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Demo

Show generation using ActivityCodeGenerator


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Additional Designtime features

Attached Properties WCF has some settings you would like to set

once on each workflow

Namespace, ServiceName, GeneratedClassName You can use attached properties for this

purpose Requires designer to add IExtenderProvider during

initialization for each attached property Requires a ExtenderProvider for each property Value can be retrieved using the GetValue()

method on the activity you attached the property to


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Additional Designtime Features Designer Validation

A validator can check if the properties that got assigned to youractivity are correct

Requires you to implement a class derived from ActivityValidator You implement the Validate method

You apply the validator to the activity using the ActivityValidator attribute At validation you have the full instantiated activity tree at your

disposal Can do complex validation cross the tree

Check if an input activity has an associated output activity when retrun

value != void Your validator is activated in compilation cycle! Therefore validation is normally used for metadata validation

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Demo

Attached properties Activity Validator


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Codeplex version

Codeplex version contains additional feature Correlation based on attributes Leaves the client from knowing and returning the

message headers At the Data/Operation contract an attribute isadded that will do the correlation

Done using a WCF behavior

Required few changes in code gen, since thereyou need to add attributes to the serviceoperations


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Q&A

More information Activities shown today

www.codeplex.com/WCFActivities

http://blogs.infosupport.com/marcelv MSDN forums Workflow SDK
http://www.codeplex.com/WCFActivitieshttp://blogs.infosupport.com/marcelvhttp://blogs.infosupport.com/marcelvhttp://blogs.infosupport.com/marcelvhttp://www.codeplex.com/WCFActivities


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Session Code: CV.27

wcf advanced activity development

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